“I found it odd that ABC would designate ADP as a hate group not based on any actual crime or action, but apparently based on their belief in religious liberty or traditional marriage,” Lankford wrote. ABC news was quoting the classification from the SPLC.

“[ADF] is national reputable law firm that works to advocate for the rights of people to peacefully and freely speak, live and work according to their faith conscience without threat of government punishment,” he wrote.

A spokesperson for ADF thanked Lankford for his defense in a statement on Friday.

“We're thankful to [Sen.] Lankford for his defense of the good, freedom-building work that ADF does and reminding ABC and all news organizations of their responsibility to Americans to report facts, not defamatory charges by activist groups.”

According to the SPLC, ADF is called both an extremist and a hate group that serves as “a legal advocacy and training group that specializes in supporting the recriminalization of homosexuality abroad, ending same-sex marriage, and generally making life as difficult as possible for LGBT communities in the U.S. and internationally.”

“I've seen them in action,” Executive Director of the LGBTQ advocacy group Freedom Oklahoma Troy Stevenson said.

Stevenson said ADF is one of the nation’s largest supporters of conversion therapy; a controversial, often physically and psychologically painful type of therapy aimed at turning homosexual men, women and children heterosexual. The practice is opposed by both the American Psychological Association and the American Counseling Association, two of the nation’s largest organizations of mental health professionals.

“It's called abuse because it is. It causes self-harm, kids are brought to suicide. This is an awful, awful thing,” he said.

Lankford also used the letter to press the president of ABC News, James Goldston, about the importance of the journalistic integrity.

“In this country we have the ability and freedom to disagree,” the senator wrote. “However, disagreement… is not the same as hate… Labeling ADF as a ‘hate group’ feeds into a narrative that the news media frequently editorializes beyond the facts.”

When asked for a comment about why the he chose to write the letter, Lankford’s office said he felt the need to defend a group he thought was unfairly labeled by the SPLC.